One person was flown by medical helicopter from a crash late Sunday near the Pittsburgh Mills, authorities said.
Frazer police Chief Aaron Scott said township officers responded to the wreck just after 9:30 p.m. along Route 28.
He confirmed the southbound lanes of the highway were shut down but referred further questions to state police, who are handling the investigation.
No one was immediately available at the state police barracks.
The road remained closed for about five hours, according to PennDOT. The agency issued an alert that Route 28 was closed between Pittsburgh Mills Boulevard and the Cheswick/Springdale exit and that it reopened around 2:30 a.m.